(Adds comment from Access Industries' Blavatnik)

By Chelsea Emery and Matt Daily

NEW YORK, Jan 6 (Reuters) - The U.S. operations of LyondellBasell, the world's third-largest petrochemical company, filed for bankruptcy protection under the weight of a massive debt load and slumping demand for its products.

The company had taken on billions of dollars in debt obligations a year ago, when billionaire Len Blavatnik led a $12.7 billion leveraged buyout of U.S. firm Lyondell by Basell of the Netherlands.

The New York bankruptcy filing on Tuesday included almost 80 units of the company and encompassed its U.S. operations and a European financing arm. The company's non-U.S. operations are not included in the Chapter 11 bankruptcy and are continuing to operate as usual.

LyondellBasell Industries [ACCEIN.UL], whose products range from fuels to chemicals and plastics, is owned by the Russian- born Blavatnik through New York-based Access Industries and is based in the Netherlands.

The U.S. operations have obtained $8 billion in debtor-in-possession financing to help fund operations, including $750 million from Access Industries.

The privately held company, which operates a massive refining and processing plant in Houston, has suffered from plunging demand for chemicals as industries such as autos, housing and electronics weakened. Tight credit markets have made renegotiating debt difficult.

NOT ALONE